Fuel pump assembly

ABSTRACT

A fuel pump assembly wherein a hydrodynamic fuel pump is mounted in a housing adjacent to an electric motor and wherein fuel issuing from the pump flows around the armature of the motor before it leaves the housing. An auxiliary pump is mounted between the rotary part of the fuel pump and the armature and is driven by the latter to insure the flow of fuel from a chamber which surrounds the armature into a clearance between the internal surface of the armature and the periphery of a fixed shaft which is mounted in the housing and in the stationary part of the fuel pump. The armature rotates on and with two friction bearings consisting of porous material and being disposed at the ends of the annular clearance. The auxiliary pump insures that fuel flows between the shaft and the bearings to thus guarantee a satisfactory positive lubrication of these bearings whenever the armature rotates.

United States Patent [191 Nusser et a1.

[ FUEL PUMP ASSEMBLY [75] Inventors: Hermann Nusser, Asperg;

Hans-Reimer Speck, Stuttgart, both of Germany [73] Assignee: Robert Bosch GmbH, Stuttgart,

, Germany [22] Filed: Nov. 19, 1973 [21] Appl. No.: 417,183

[30] Foreign Application Priority Data Dec. 21, 1972 Germany 2262569 [52] U.S. Cl. 417/368, 310/62 [51] Int. Cl. F04b 17/00, l-102k 9/06, F04d 5/00 [58] Field of Search 417/368; 310/62, 63; 415/53 T, 59,143

[5 6] References Cited UNITED STATES PATENTS 2,993,449 7/1961 Harland 310/62 X 3,302,583 2/1967 Hunt 310/63 X 3,801,231 4/1974 Nusscr et al.. 415/143 3,836,291 9/1974 Bottcher 417/423 1 Mar. 25, 1975 Primary E.raminer-C. J. Husar Assistant ExaminerRichard E. Gluck Attorney, Agent, or Firm-Michael S. Striker [57] ABSTRACT A fuel pump assembly wherein a hydrodynamic fuel pump is mounted in a housing adjacent to an electric motor and wherein fuel issuing from the pump flows around the armature of the motor before it leaves the housing. An auxiliary pump is mounted between the rotary part of the fuel pump and the armature and is driven by the latter to insure the flow of fuel from a chamber which surrounds the armature into a clearance between the internal surface of the armature and the periphery of a fixed shaft which is mounted in the housing and in the stationary part of the fuel pump. The armature rotates on and with two friction bearings consisting of porous material and being disposed at the ends of the annular clearance. The auxiliary pump insures that fuel flows between the shaft and the bearings to thus guarantee a satisfactory positive lubrication of these bearings whenever the armature rotates.

10 Claims, 4 Drawing Figures EAR 2 5 i975 SHEET 2 [IF 3 Fig.3.

Fig.4

45 r ||||||I|lllllllllllllllllllll FUEL PUMP ASSEMBLY BACKGROUND or THE INVENTION The present invention relates to apparatus for conveying a fluid, particularly liquid fuel, and more particularly to improvements in apparatus or assemblies wherein a motor drive the rotary part of a pump and is confined in a housing which also surrounds the pump. Still more particularly, the invention relates to improvements in hydraulic aggregates wherein a hydrodynamic pump is driven by the rotary components of an electric motor and wherein the fluid which is being advanced by the pump flows around the rotary parts of the motor and lubricates one or more bearings for such rotary parts.

Apparatus of the just described character are often used for conveying a liquid fuel. They exhibit a number of important advantages, such as simplicity of design, compactness and absence of any special provisions to insure satisfactory lubrication of bearings for the rotary parts of the pump and motor. As a rule, fuel which is being conveyed by the pump contacts the outer ends of the bearings on or with which the rotary parts of the motor rotate whereby such contact suffices to insure at least some lubrication of the bearings. A drawback of these apparatus is that the lubrication of bearings is not always satisfactory which brings about excessive wear and necessitates frequent inspection of the apparatus and replacement of worn components. In many instances, such unpredictable lubrication does not suffice to avoid premature and excessive wear upon the relatively movable parts of the pump and/or motor.

SUMMARY OF THE INVENTION An object of the invention is to provide an apparatus for conveying a fluid, particularly a liquid fuel, wherein the rotary part or parts of the pump are directly driven by the rotary parts of an electric motor and wherein the bearings for such rotary parts are invariably lubricated in a predictable manner which is much more reliable and satisfactory than in heretofore known motor-pump aggregates.

Another object of the invention is to provide a fuel pump assembly withv novel and improved auxiliary .pump means for insuringv positive lubrication of bearings for the rotary parts of the fuel pump and its motor.

A further object of the invention is to provide a pump assembly wherein the auxiliary pump occupies little room, wherein the auxiliary pump occupies space which is readily available, and wherein the auxiliary pump insures continuous lubrication of each and every bearing between the rotary parts of the pump and motor and the stationary part or parts on which the rotary parts rotate.

An additional object of the invention is to provide an apparatus of the above outlined character wherein a hydrodynamic pump is driven by an electric motor and is surrounded by a housing which also receives the motor and enables the fluid toflow around the rotary parts of the motor before it leaves the housing.

The invention is embodied in an apparatus for conveying a fluid, particularly liquid fuel, which comprises a hydrodynamic pump having a rotary part (such pump may constitute a so-called side channel pump having a rotary impeller), an electric motor having an armature which is coaxial with and is arranged to drive the rotary part of the pump (the armature may be provided with a plastic casing which may be made integral with the rotary part of the pump), a housing which surrounds the pump and the motor and defines achamber which receives pressurized fluid from the pump and surrounds the armature, a shaft which is mounted in fixed support means provided therefor in the housing and/or in the stator of the pump and is coaxial with the armature, a pair of spaced apart bearings which surround the shaft and at least one of which is disposed between the armature and the shaft, a clearance or space which is defined by the shaft and armature and extends between the two bearings, and auxiliary pump means driven by the armature and serving to effect the flow of fluid between the chamber and the space so that the fluid which enters the space lubricates the bearings.

The bearings preferably rotate with the armature, and one thereof may be installed in the rotary part of the pump. At least one of these bearings may consist of a porous material, such as a suitable sintered metal.

The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims. The improved fuel pump assembly itself, however, both as to its construction and its mode of operation, together with additional features and advantages thereof, will be best understood upon perusal of the following detailed description of certain specific embodiments with reference to the accompanying drawing.

BRIEF DESCRIPTION OFTHE DRAWING FIG. 1 is an axial sectional view of a fuel pump assembly which embodies the invention, the section being taken in the direction of arrows as seen from the line II of FIG. 2;

FIG. 2 is a sectional view substantially as seen in the direction of arrows from the line II?-II of FIG. 1;

FIG. 3 is an axial sectional view of the rotor of the fuel pump assembly; and

FIG. 4 is an elevational view of the structure shown in FIG. 3.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1' illustrates a compact fuel pump assembly which comprises a hydrodynamic fuel pump 1 of the type known as side channel pump and an electric motor 2. The pump 1 and the motor 2 are installed in an elongated housing including a first or main section 3 and a second section 4. The fuel flows in the direction indicated by arrows, i.e., it enters the housing at one end by way of an inlet 5 and flows through the pump 1, thereupon through the motor 2 in the longitudinal direction of the housing, and leaves at the other end of the housing by way of an outlet 22. The inlet 5 and outlet 22 are located at the opposite axial ends of the housing and respectively constitute component parts of the housing sections 3 and 4. The section 3 contains a side channel plate 6 which constitutes the stationary part of the pump 1 and is located downstream of the inlet 5 and is surrounded by an annular sealing element 7. The plate 6 is rigid with and its central portion constitutes a bearing for a shaft 8 whose axis coincides with the axis of the housing section 3. A rotor 9 which is rotatable on the shaft 8 includes the rotary parts of the motor 2 and the rotary part or impeller 10 of the pump 1. The rotary parts of the electric motor 2 include an armature 11 with laminae 12, a commutater l3, friction bearings 14 and 14, and a synthetic plastic casing or enclosure 15 for the armature 11. The impeller 10 preferably also consists of synthetic plastic material and may be made integral with the casing 15 of the armature 11.

The housing section 3 resembles a cup whose bottom wall is provided with the inlet 5; this section contains a hollow enclosure 17 in the form of an elongated cylinder which is mounted on the side channel plate 6 and carries magnetic segments 18 surrounding the casing 15 for the armature 11. As shown in FIG. 1, the centers of the segments 18 are located to the left of the center of the armature 11 so that the latter is biased in a direction toward the plate 6. The bearing 14 which is surrounded by the impeller and is located between the armature l1 and the plate 6 thus acts not only as a radial bearing but also as an axial or thrust bearing be cause the magnetic segments 18 tend to move the armature 11 toward the pump 1. The bearing 14 can abut against the plate 6. The width of the gap or clearance between the plate 6 and impeller 10 depends on the extent to which the bearing 14 extends to the left beyond the casing 15.

The section 4 of the housing acts not unlike a closure or plug for the right-hand end of the section 3. A ringshaped sealing element 19 is interposed between the internal surface of the right-hand portion of the section 3 and the external surface of the left-hand portion of the section 4. The section 4 contains rod-shaped carbon electrodes 20 which are biased by helical springs 21 so as to bear against the commutater 13. A ringshaped central portion 23 of the second section 4 of the housing acts as a support for the shaft 8.

As shown in FIGS. 1 and 2, fuel which enters the housing section 3 via inlet 5 flows into an inlet opening or suction port 25 of the side channel plate 6 and enters the side channel 26 proper. After leaving the channel 26, fuel flows through a radially extending pressure port 27 and into an annular groove 28 of the plate 6. The pressure port 27 communicates with an axially parallel channel 29 which can communicate with the suction chamber SC of the pump 1 by way of a relief valve 30. The valve 30 includes a platelike valve member 31 having an end portion 32 which is hingedly connected to the plate 6. The valve member 31 has a bore 33 which receives the shaft 8 with some clearance so as to allow the valve member to pivot at 32. A helical spring 34 which reacts against a clamping ring or retainer 35 on the left-hand end portion of the shaft 8 bears against the valve member 31in the region of the bore 33 so as to urge the lower end portion of the valve member (as viewed in FIG. 1) against the plate 6 in the region of the left-hand axial end of the channel 29. The clamping ring 35 is preferably adjustable axially of the shaft 8 to thereby change the bias of the spring 34 and to thus determine that fuel pressure in the channel 29 which suffices to open the valve 30 so that fuel can spill from the groove 28 into the chamber SC.

That portion of the side channel plate 6 which is located between the suction port 25 and the pressure port 27 is provided with a cavity or recess 37 which is located at the same distance from the axis of the shaft 8' as the channel 29. The recess 37 communicates with the groove 28 by way of a radially extending channel 38 which insures that the section or portion 39 of the side channel 26 in the plate 6 of the pump 1 is relieved. The width of the section or portion 39, as considered in the radial direction of the plate 6, is approximately half the width of the main portion of the channel 26 (see FIG. 2). It will be seen that the portion 39 registers with the recess 37, as considered in the radial direction of the pump 1.

Fuel which enters the groove 28 can flow into an annular groove 40 of the impeller 10, and the groove 40 is in communication with a motor chamber 42 by way of channels or ports4l (see FlG. 3). The chamber 42 surrounds the casing 15 and communicates with the outlet 22. The space between the casing 15 and the impeller 10 receives an enlarged portion or pumping member 44 which extends diametrically of the shaft 8 (see FIGS. 1 and 4) and comprises two identical halves which are mirror symmetrical to each other with respect to a plane including the axis of the shaft 8. The two halves of the enlarged portion 44 are formed with coaxial passages or bores 45 which communicate with an axial bore 46 of the rotor 9. The common axis of the bores 45 is preferably normal to the axis of the shaft 8. The surfaces surrounding the bores 45 are slightly conical surfaces which diverge gradually radially outwardly. The enlarged portion 44 and its bores or passages 45 constitute a simple auxiliary pump. FIG. 1 shows that the bore 46 receives the shaft 8 with some clearance, i.e., the parts 8 and 10 define an elongated cylindrical space which is indicated at 47. When the rotor 9 rotates, the centrifugal effect in the bores 45 of the reinforced portion 44 of the rotor 9 generates'a slight suction in the space 47, and such slight suction suffices to draw fuel into the space 47 through the bearings 14 and 14. This insures an automatic positive lubrication of the rotor 9 and shaft 8 as well as of the bearings 14 and 14' so that the bearings are properly lubricated at all times. The bearings 14 and 14 preferably consist of porous material, such as a sinteredmetal. HO. 4 shows that the two halves of the reinforced portion 44 of the rotor 9 alternate with axially parallel ribs or webs 43 which are angularly offset with respect to the halves of the portion 44 by The webs 43 extend between the casing 15 and the impeller 10. The bearings 14, 14 are located at the front and rear ends of the space 47 and are rigid with the rotor 9. The inner ends of the bores or passages 45 communicate with the space 47 adjacent to the bearing 14, and the outer ends of these passages communicate with the chamber 42.

An advantage of the auxiliary pump 44, 45 is that its pumping member 44 need not be machined with precision and that this member mayf'constitute an integral part of the rotor 9- between the rotarypart 10 of the pump 1 and the casing 15 of the armature 11. The auxiliary pump insures a positive lubrication of the'friction bearings 14, 14' and its space requirements are negligible; in fact, this auxiliary pump occupies space which is invariably available in the aggregate.

It is clear that the armature 11 can rotate on two or more friction bearings. Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features which fairly constitute essential characteristics of the generic and specific aspects of our contribution to the art and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the claims.

'part; an electric motor having an armature arranged to drive said rotary part; a housing surrounding said pump and motor and defining a chamber receiving pressurized fluid from said pump and surrounding said armature; a shaft mounted in said housing coaxially with said armature; a pair of spaced apart bearings surrounding said shaft, at least one of said bearings being disposed between said shaft and said armature, said shaft and said armature defining a space extending between said bearings; and auxiliary pump means driven by said armature and arranged to effect the flow of fluid between said chamber and said space whereby the fluid entering said space lubricates said bearings.

2. Apparatus as defined in claim 1, wherein said bearings are friction bearings which rotate with said armature with respect to said shaft.

3. Apparatus as defined in claim 1, further comprising a support provided in said housing for said shaft.

4. Apparatus as defined in claim 1, wherein said auxiliary pump means comprises a pumping member disposed between said rotary part and said armature and having at least one passage one end of which communicates with said chamber and the other end of which communicates with said space.

5. Apparatus as defined in claim 4, wherein said passage extends substantially radially of said shaft and its cross-sectional area increases gradually from said other toward said one end thereof.

6. Apparatus as defined in claim 4, wherein said pumping member comprises two coaxial passages extending at right angles to the axis of said shaft.

7. Apparatus as defined in claim 1, wherein said rotary part is rigid with said armature and forms therewith a rotor having an axial bore for said shaft, the diameter of said bore exceeding the diameter of said shaft to thus provide said space between the internal surface of said rotor and the external surface of said shaft, said bearings being located in and at the ends of said bore and being rigid with said rotor.

8. Apparatus as defined in claim 1, wherein at least one of said bearings is a porous friction bearing.

9. Apparatus as defined in claim 1, wherein said pump is a side channel pump.

10. Apparatus as defined in claim 1, wherein said housing is elongated and has a fluid-admitting inlet at one end and a fluid-discharging outlet at the other end thereof, said pump being adjacent to said inlet and said chamber communicating with said outlet. 

1. Apparatus for conveying a fluid, particularly liquid fuel, comprising a hydrodynamic pump having a rotary part; an electric motor having an armature arranged to drive said rotary part; a housing surrounding said pump and motor and defining a chamber receiving pressurized fluid from said pump and surrounding said armature; a shaft mounted in said housing coaxially with said armature; a pair of spaced apart bearings surrounding said shaft, at least one of said bearings being disposed between said shaft and said armature, said shaft and said armature defining a space extending between said bearings; and auxiliary pump means driven by said armature and arranged to effect the flow of fluid between said chamber and said space whereby the fluid enteriNg said space lubricates said bearings.
 2. Apparatus as defined in claim 1, wherein said bearings are friction bearings which rotate with said armature with respect to said shaft.
 3. Apparatus as defined in claim 1, further comprising a support provided in said housing for said shaft.
 4. Apparatus as defined in claim 1, wherein said auxiliary pump means comprises a pumping member disposed between said rotary part and said armature and having at least one passage one end of which communicates with said chamber and the other end of which communicates with said space.
 5. Apparatus as defined in claim 4, wherein said passage extends substantially radially of said shaft and its cross-sectional area increases gradually from said other toward said one end thereof.
 6. Apparatus as defined in claim 4, wherein said pumping member comprises two coaxial passages extending at right angles to the axis of said shaft.
 7. Apparatus as defined in claim 1, wherein said rotary part is rigid with said armature and forms therewith a rotor having an axial bore for said shaft, the diameter of said bore exceeding the diameter of said shaft to thus provide said space between the internal surface of said rotor and the external surface of said shaft, said bearings being located in and at the ends of said bore and being rigid with said rotor.
 8. Apparatus as defined in claim 1, wherein at least one of said bearings is a porous friction bearing.
 9. Apparatus as defined in claim 1, wherein said pump is a side channel pump.
 10. Apparatus as defined in claim 1, wherein said housing is elongated and has a fluid-admitting inlet at one end and a fluid-discharging outlet at the other end thereof, said pump being adjacent to said inlet and said chamber communicating with said outlet. 